Maternal thyroid function at 11 to 13 weeks of gestation and subsequent development of preeclampsia.

OBJECTIVE To determine if maternal thyroid function in the first trimester is altered in pregnancies that subsequently develop preeclampsia (PE). METHODS Mean arterial pressure (MAP), uterine artery pulsatility index (PI) maternal serum thyroid stimulating hormone (TSH), free thyroxine (FT4) and free triiodothyronine (FT3) at 11 to 13 weeks of gestation were measured in 102 singleton pregnancies that subsequently developed PE, and the values were compared to the results of 4318 normal pregnancies. RESULTS In both the PE groups that required delivery before 34 weeks (early-PE) and the late-PE group, compared with the unaffected group, the median MAP multiple of the normal median (MoM) and uterine artery PI MoM were significantly increased. In late-PE but not in early-PE, compared with the unaffected group, the median TSH MoM was significantly increased and the median FT4 MoM was decreased. Logistic regression analysis demonstrated that TSH MoM provided a significant contribution in the prediction of late-PE. CONCLUSION Impaired thyroid function may predispose to the development of late-PE, and measurement of maternal serum TSH can improve the prediction of late-PE provided by a combination of factors in the maternal history and the measurements of MAP and uterine artery PI.